Disc Cutters are used in the mining industry to cut through rock and create tunnels and other cavities. Multiple disc cutters are located at various positions on the face of a tunnel boring machine (TBM) where the placement of the cutters balance thrust force across the face of the TBM to maximize penetration. The cutter head rotates at 4 to 10 rpm and breaks rock into large chips, which fall into buckets rotating with the head where the buckets lift the chips to a conveyer belt to discharge the rock chips for final transport out of a tunnel. The typical TBM cuts 30 to 40 meters of tunnel per day.
A typical state of the art disc cutter is a single disc cutter that has a disc diameter of 17 to 19 inches. The edge of the cutter, where contact with the rock is made, is a tool steel ring. A good ring requires hardness but also must be tough and have a high impact resistance for long wear. The industrial standard ring is H13 tool steel. Some proprietary alloys are available for steel rings for blade cutters; including alloys where particles of tungsten carbide are included in the matrix of the steel. A significant portion of the time to bore a tunnel, approximately 40%, is down time with the majority of the down time is required for the replacement of disc cutters on the face of the TBM. To this end an improvement of the wear resistance of the disc cutter can increase the energy efficiency of the boring process by as much as 25%.
State of the art disc cutter rings are uncoated metals. When coatings have been applied to cutting surfaces for disc cutter, they have been applied as a continuous coating. These continuous coatings have failed due to their propensity for spallation when subjected to substantial alternating cycles of tensile and compressive strain, like that of a disc cutter during boring into rock. There remains a need for an abrasive surface with superior hardness and wear resistance for use on disc cutters or other devices that experience significant abrasive wear, high point loads, and large shear stresses during use. Such devices include bits in road headers, cutting tools, augers, earth moving equipment, blades, teeth, print and dye machines, paving equipment and road removal equipment.